The present invention relates to the field of communications and, more particularly, to radio communications.
Included among the wireless communications systems in use today are low-power wireless systems that are used to cover a limited geographic area, such as an office, a building, a campus or the like. An example of such a wireless system is a pico cell network. These wireless systems may be designed for use by wireless terminals that are also configured to access, for example, a public cellular network, such as a cellular network complying with IS-41, IS-136 or other standards. These systems typically include a plurality of radio heads, i.e. transceiver units that function in a manner similar to base stations of a conventional cellular network.
Radio heads may be located in an indoor environment. Radio heads can be geographically distributed throughout, for example, buildings. The radio heads within these buildings can all be linked to a central control cabinet that contains control processing. A mobile switching center (MSC) can communicate with the control cabinet over a leased line that complies with a carrier protocol, such as a T1, E1, or J1 carrier protocol. Each carrier protocol can support a fixed number of channels or timeslots within a frame for communicating control, voice, and data information between the mobile switching center and a control cabinet over a carrier bus. For example, the T1 carrier protocol can support 24 channels or timeslots per frame.
The MSC can communicate control information to the control cabinet over a control signaling link (CSL) (64 kb/s PCM timeslots). Conventional systems typically use a control radio interface (CRI) that supports a single CSL for all control information communicated between the MSC and the control cabinet. A single CSL can occupy one timeslot per frame on the carrier bus or, in other words, 1 of 24 timeslots per frame can be dedicated to control information.
The control cabinet may include a regional processor that may process the CSL, i.e. the control information. Once the CSL has been processed, the control information can be forwarded to a plurality of transceivers located inside each of the radio heads connected to the control cabinet. The connection between the control cabinet and the radio heads may also comply with a carrier protocol, such as T1, E1 or J1. Thus, this link may include a fixed number of timeslots, for example, 24 timeslots in the case of a T1 carrier protocol. Each radio head uses the first 8 timeslots and shifts the remaining timeslots out to the next radio head. In other words, the connection between the control cabinet and the radio heads is not a bus. This link may not be error free, thus, an error correction scheme may typically be performed.
A conventional radio head typically includes a plurality of transceivers. Since the signal processing is performed at the control cabinet by the regional processor, each of these transceivers may receive a dedicated voice timeslot and a dedicated control timeslot from the control cabinet to the transceiver. Therefore, each of the transceivers may utilize 2 of the 24 timeslots (in the case of a T1 carrier protocol) on the link between the control cabinet and the radio heads. Assuming that each radio head has four transceivers, only three radio heads utilizing 8 timeslots each may utilize a single T1 line. Accordingly, the existing architecture may limit the number of radio heads that, for example, a pico cell network, may support and may introduce unnecessary delay in the system.